Man, there are a few things you have to keep in mind here.
First, the judge that determined Abrego Garcia is MS-13 was an immigration judge. This was not a criminal case. The police/district attorney in Prince George did not bring any charges against him. Immigration judges/courts are very different from criminal courts. They are making administrative determinations.
Second, the hearing where this determination occurred was a bond hearing by the immigration judge. It was to determine if he should be granted bail or held until his immigration case is complete. In this situation, the standard is that ICE/DHS claims Abrego Garcia is a threat or flight risk. It is up to Abrego Garcia to prove to the judge that he is not a threat to the community. It is a very high bar putting the onus on the defendant to prove a negative. And the judge is completely reasonable in being cautious and not granting release. But it is a very different standard than anything we'd see in a criminal case.
Third, Fox News, Pam Bondi and the White House keep talking about "two judges determined he's MS-13". The second judge was handling the appeal of the bond hearing. Still an immigration judge, still not a criminal case. In this appeal, the judge is not tasked with determining whether he's MS-13. Instead, the appeal judge has a narrow task of determining whether they original judge clearly erred in making the bond decision. Denying the appeal just means the judge determines that there was some evidence originally presented and the original judge was being reasonably cautious.